This substance is such a commonplace element in our lives that we take it for granted, like air and water and the soil itself; yet the generation that fought the Civil War knew practically nothing of steel. They were familiar with this metal only as a curiosity or as a material used for the finer kinds of cutlery. How many Americans realize that steel was used even less in 1865 than aluminum is used today? Nearly all the men who have made the American Steel Age--such as Carnegie, Phipps, Frick, and Schwab--are still living and some of them are even now extremely active. Thirty-five years ago steel manufacture was regarded, even in this country, as an almost exclusively British industry. In 1870 the American steel maker was the parvenu of the trade. American railroads purchased their first steel rails in England, and the early American steel makers went to Sheffield for their expert workmen. Yet, in little more than ten years, American mills were selling agricultural machinery in that same English town, American rails were displacing the English product in all parts of the world, American locomotives were drawing English trains on English railways, and American steel bridges were spanning the Ganges and the Nile. Indeed, the United States soon surpassed England. In the year before the World War the United Kingdom produced 7,500,000 tons of steel a year, while the United States produced 32,000,000 tons. Since the outbreak of the Great War, the United States has probably made more steel than all the rest of the world put together. "The nation that makes the cheapest steel," says Mr. Carnegie, "has the other nations at its feet." When some future Buckle analyzes the fundamental facts in the World War, he may possibly find that steel precipitated it and that steel determined its outcome.